Robert Lustig is a paediatric endocrinologist at the University of California who specialises in the treatment of childhood obesity. A 90-minute talk he gave in 2009, titled Sugar: The Bitter Truth, has now been viewed more than six million times on YouTube. In it, Lustig argues forcefully that fructose, a form of sugar ubiquitous in modern diets, is a “poison” culpable for America’s obesity epidemic.

A year or so before the video was posted, Lustig gave a similar talk to a conference of biochemists in Adelaide, Australia. Afterwards, a scientist in the audience approached him. Surely, the man said, you’ve read Yudkin. Lustig shook his head. John Yudkin, said the scientist, was a British professor of nutrition who had sounded the alarm on sugar back in 1972, in a book called Pure, White, and Deadly.

“If only a small fraction of what we know about the effects of sugar were to be revealed in relation to any other material used as a food additive,” wrote Yudkin, “that material would promptly be banned.” The book did well, but Yudkin paid a high price for it. Prominent nutritionists combined with the food industry to destroy his reputation, and his career never recovered. He died, in 1995, a disappointed, largely forgotten man.

Perhaps the Australian scientist intended a friendly warning. Lustig was certainly putting his academic reputation at risk when he embarked on a high-profile campaign against sugar. But, unlike Yudkin, Lustig is backed by a prevailing wind. We read almost every week of new research into the deleterious effects of sugar on our bodies.